blob: b690c7252623fdfa6063f4b62554b37c2a9c32fa [file] [log] [blame]
// Copyright 2019 Google LLC.
// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
// Image Diff: Provides a metric for measuring the difference between two encoded images. Prints
// out a single floating-point number between 0.0 and 1.0; 0 means that the images are identical; 1
// means that each pixel is maximally different in each channel. A non-zero return value indicates
// that something went wrong.
#include "include/codec/SkCodec.h"
#include "include/core/SkBitmap.h"
#include "include/core/SkData.h"
#include "include/core/SkPixmap.h"
#include "include/core/SkSize.h"
#include <cmath>
#include <cstdio>
int main(int argc, char** argv) {
if (argc != 3) {
const char usage[] = "\nUsage:\n %s {FILE1}.png {FILE2}.png\n\n";
fprintf(stderr, usage, argv[0]);
return 1;
}
SkBitmap bm[2];
for (int i = 0; i < 2; ++i) {
const char* path = argv[i + 1];
if (std::unique_ptr<SkCodec> codec =
SkCodec::MakeFromData(SkData::MakeFromFileName(path))) {
bm[i].allocN32Pixels(codec->dimensions().fWidth, codec->dimensions().fHeight);
if (SkCodec::kSuccess == codec->getPixels(bm[i].pixmap())) {
continue;
}
}
fprintf(stderr, "\nBad file: '%s'.\n\n", path);
return 2;
}
SkISize dim = bm[0].dimensions();
if (dim != bm[1].dimensions()) {
fprintf(stderr, "\nImages must be same size: (%d,%d) != (%d,%d)\n\n",
dim.fWidth, dim.fHeight, bm[1].dimensions().fWidth, bm[1].dimensions().fHeight);
return 3;
}
int64_t totalDiffs = 0; // Manhattan distance in ARGB color-space.
for (int y = 0; y < dim.fHeight; ++y) {
const uint8_t* row1 = reinterpret_cast<const uint8_t*>(bm[0].pixmap().addr32(0, y));
const uint8_t* row2 = reinterpret_cast<const uint8_t*>(bm[1].pixmap().addr32(0, y));
for (size_t i = 0; i < (size_t)dim.fWidth * (size_t)4; ++i) {
totalDiffs += std::abs((int)row1[i] - (int)row2[i]);
}
}
printf("%g\n", (double)totalDiffs /
((uint64_t)255 * 4 * (uint64_t)dim.fWidth * (uint64_t)dim.fHeight));
return 0;
}